1. Field of the Invention
The invention is in the field of test apparatus employing a colorimeter flow cell for determining the quantitative analysis of bubble separated segments of fluids. Fluids as herein used refer both to liquids and gases.
2. Description of the Prior Art
In U.S. Pat. No. 3,804,593 by William J. Smythe et al, an apparatus and method is described wherein an automatic analysis apparatus includes an indexible table supporting a plurality of liquid sample containers, a stationary reagent liquid container, two off-take tubes, one tube insertable in a presented thereto sample container, the other tube insertable in the reagent container, means for concurrently inserting both tubes repeatedly into their respective containers to provide a flowing stream of segments of liquid sample interspersed by air segments, and a smilar stream of segments of reagent. These streams are merged to form a stream of liquid and air segments, which stream of liquid and air segments is passed through the sight passageway of a flow cell of a colorimeter. A recorder is coupled to the detector side of the colorimeter through an electrical switch which interrupts the operation of said recorder whenever the sample reagent segment volume is not equal to the volume of the sight passageway of the flow cell, thereby shutting down the recorder for some period of time in order to allow the air segment to completely clear the sight passageway of the flow cell.
In allowing the segments to remain intact within the sight passage of the flow cell, system efficiency is significantly increased; however, this advantage is practically deficient when the recorder must be shut down by a switching means in order to allow the sight passage of the flow cell to become completely clear of air segments. If the recorder were allowed to continue in operation during the progression of an air segment through the sight passage of the flow cell, the readout of the recording would show corresponding spikes or non essential data which clutters the desired sample curve data. Another advantage of the present invention over the prior art is in that irregularly spaced air bubbles can be used with the comparator but, the fluid segment volume must be at least equal to the volume of the sight passageway of the flow cell.
R. L. Habig et al in Clinical Chemistry 15, 1045 (1969) and W. H. Walker et al in Clin. Chim. Acta 27, 421 (1970) taught removing the air bubble or debubbling the segmented fluid sample to be tested at a point just prior to entry into the sight passage of the flow cell. Habig et al also taught elimination of the need for a debubbler by utilizing a bubble gating flow cell. Their device monitored flow cell conductance and deactivated the system output when bubbles passed through the photometer flow cell. This latter technique, although useful for testing, would not withstand daily technician use and abuse. The herein described invention overcomes the deficiencies of the conductance gate. In the case of utilizing a debubbler the recorder is allowed to operate continuously, but the test results are less efficient because of the dispersion of the sample.